


Master Kurama

by IruMinO



Category: Kuroshitsuji | Black Butler, Naruto
Genre: Alternate Universe - Canon Divergence, Canon-Typical Violence, Crossover, Gen
Language: English
Status: In-Progress
Published: 2019-03-04
Updated: 2019-03-04
Packaged: 2019-11-09 08:38:12
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 5,202
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17998538
Author URL: https://archiveofourown.org/users/IruMinO/pseuds/IruMinO
Summary: In which Kurama summons unexpected underling from his past for the sake of his survival and ended up adopting his newly orphaned jailer.(a rewrite from my story in fanfiction.net "Old Master? New Master!" because the site has become so troublesome)





	1. The Long Awaited Summon

**Author's Note:**

> Disclaimer: I do not own Naruto or Kuroshitsuji.

This story, like most of story in this world, begins with the introduction of the main character, which happens to be a little blond baby boy of fifteen months in the name of _Uzumaki_ Naruto which later people would know him with another name. This particular baby has great history since the moment he was born, but that was a story for another time. Based on appearance alone most people in Konoha will notice that something is quite different about him, and we’re not talking about how adorable he absolutely is, with strands of gold atop of his little head, his fair skin that looks as smooth as porcelain, the healthy glow of his rosy cheeks adorned with whiskers like marks that complete his impression of a kitten, and of course the pair of mischievous crystal blue eyes that glitter like a pair of aquamarines when he cries. If you’re wondering that maybe the whiskers like marks were the thing that makes him different, you’d be wrong. No, physical marks are fairly common in a hidden village. People from various clans brags about the marks that differs them from the average people, how the marks make them special.

So no, the whiskers like marks are just one of the distinguishing features of the child.

No one really knows where little Naru-chan comes from. For all they know he’s just another orphan, his parents slain by the great terrible demon fox a year and half before. This baby is a symbol of bad omen they says, being born on that fateful day. The superstitious villagers shun him for that fact alone; others even believed that the helpless baby is the incarnation of Nine Tails, the Demon Fox. Cry of outrages filled the night after the demon fox felled by their Hokage, taking the life of the young kage with it. Words spread fast about the unknown baby with the marks of the fox, and people demanded his blood to be spilled in vengeance.

The Third Hokage denied them.

Sarutobi Hiruzen, The Professor, the hero of the Second Shinobi Great War, denied them their vengeance, even after acknowledging the baby’s connection with the demon fox.

The baby is not the incarnation of Nine Tails, but its vessel. Their slain Fourth Hokage died sealing the dreadful demon fox in a baby. People weep for the fate of their hero and loath the existence of the human vessel of the calamity known as Nine Tails.

The baby is different from any other baby in Konoha because everyone knows about him and most cannot pretend to be neutral to his existence. The matrons of the orphanage are very reluctant to care for him, the other children are told to avoid him, and others deny his very existence.

Being fifteen months old, baby Naruto doesn’t understand why he’s always alone even though he can hear voices behind his door; big voices, little voices, kind voices, raised voices, and even laughter. The people that come to his room deals with him in silence, and with his limited capability of feeling, he feels sad and afraid.

Today is another day of silence, even after he tried to provoke the matron’s reaction by throwing tantrum very loudly; it only made her leaves. Naruto cries himself to sleep tonight.

So, this is the sight that happens upon a demon that is summoned into this room, a demon of great renown, bringer of tragedies and calamities, and yet, even such demon is not top of the food chain. Though, for his reputation sake, there is only one other demon capable of summoning him on a whim—The Nine Tailed Demon Fox, Kurama, his Old Master from hundreds of years ago, one who has lost contact with him from that fateful day. To think that now of all time he would summon him is a bit surprising considering his master didn't even try to even contact him earlier than this.

Carefully, the demon masks his presence and casts a silent spell to ward off any intruder, and moves towards the crib where baby Naruto is asleep with tears tracks on his cheeks. Upon laying his eyes on the child, Sebastian is overcome by familiar pleasant quiver whenever his eyes cast upon a cat. In the back of his mind, the demon sense that cannot be fooled with mere false flesh, knows that his master is within the small human, trapped in a powerful jail woven with formidable seals. Caressing the tears stained cheeks of the child, he concentrates briefly and dives into the baby's mindscape where he finds Kurama, the great old fox, in his humanoid form with slacked jaw upon seeing his smitten expression, it seems like his liege forgets his quirk.

"I know you adore the mortal realm's felines, but please don't make these faces in my presence!" Kurama admonishes him with a hint of mortification in it.

"I shall try my best Kurama-sama," he replied with a pleasant smile, slightly happy that his master didn't change much even in prison, ever so proper and uptight, though he does have his moments.

The Nine Tails huffs, “See that you do.”

There is a haughty silence until the fox suddenly grinned, “I’m going to call you Sebastian from now on.”

The Demon widened his eyes in surprise. Noticing this, Kurama’s grin grows even wider, his fangs gleaming white, "Ah, yes. There's little you can hide from me. To think that a mortal named you after a dog, a loyal dog that rather scared him, no less?"

Feeling resigned Sebastian just sighs, "Then, why now?"

It’s Kurama’s turn to sigh, “It was madness and my previous vessels didn’t let me use my hands,” the fox admits.

Sebastian eyes flicker to his master’s body, searching for signs of the implied injuries; only to finds none—as expected, his master regeneration ability is impeccable as always. However, the spiritual wound is so great he wonder why he didn’t notice before. The fox’s spiritual powers and presence are half of what it used to be. A look of alarm crosses his face which his master notices, prompting another sigh from the demon fox.

“Notice it didn’t you?” the fox asked rhetorically, not even waiting for a response he continues, “The one responsible for sealing me inside this babe separated my core into yin and yang, then he put the yang part—me, into this child, his own child. And then he sealed my yin part into himself and he had the gall to be devoured by that sick god of death. My other half is inaccessible indefinitely, unless you have the skill to make a god of death puke.”

The demon now named Sebastian raises an eyebrow, silently asking after his master sanity.

“I’m fine, just a wistful thinking, if you can do it, I can get out of here easier, so much easier,” the fox lets out a long sigh.

“I see. How do you wish to proceed from here, My Lord?”

"We need to get out of here and prepare for war, this peace will not last a decade. For now, I'll give you a history lesson, about me—something you haven’t heard before, I know I’m not so forthcoming with my origin, but back then you didn’t yet need to know about it. From this point onward, however, you have to know. This world where I come from is rather different from the world you just came from and also rather different from the Underworld. Make yourself comfortable, this is a fairly long tale."

"Yes, My Lord," Sebastian answered solemnly.

Thus, began Sebastian history lesson; starting from the day Kurama was born what prompt it and how all of those histories are relevant to the world of living even now and especially regarding the blond baby whose mind they occupied.

And while Sebastian is thrumming with restless energy from his master tales, because learning something that he will not even dream about, his master's _personal_ history—something he always wonder about, seeing as he could not dig anything worth about his master in the past, even with his flawless information gathering skills, but now the ever so mysterious master he serves, willingly tells him about himself, about his powerful father, his eight siblings scattered across the realm, and about the wars started because of them. He used to think that his master is an only child if he ever had progenitor/parent, or a single entity of power materialized into existence by the grace of someone or something so powerful that even _their_ mere creation is able to subjugate the entirety of the Underworld in a single decisive combat.

However, the reality is even more bizarre. A father that was also a vessel of the most powerful beings in this realm that didn’t go mad with the power he possessed, about treacherous human siblings that wage wars with every rebirth they took, because of a petty jealously, and how finally a single human has the power to subjugate every tailed beasts only to give them to his enemies to make peace that didn’t even last long. If he thinks human in position of power is complicated before, then human in position of power _with supernatural ability_ is downright convoluted in his opinion. His master should have the courtesy of providing a bottle of a strong spirit before beginning his complex tale, some _Magma Tears_ or _Liquid Thunder_ would have gone nicely.

Sebastian is impressed despite himself, not for their possession of supernatural power—though, that’s impressive in itself, but for the sheer possibilities their powers, just how advanced this realm would be if the people in power possess the slightest bit more insight. It’s almost a pity that this realm is still stuck in the age of clan rivalries that the slightest provocation will lead to war, an era sprinkled with petty disputes over the tiniest concern.

Not that he’s complaining of course, because in the realm of chaos, a demon thrives, and some of the most delectable souls are forged by the chaos itself—But of course, no one is as delicious as his master, he sensed it before, long ago when they first met face to face, under layers upon layers of hatred his master possess, lay a soul unlike he ever known before.

Now that he knows the story, he understand why his master soul is so out of the ordinary; it’s because his master’s soul is just one part of the soul of a great being—but then sould shard becomes another powerful entity entirely, along with the other eight shards, but with his Yin self separated, the amount of hatred cloaking his master soul is not able to conceal the soul underneath, a beautiful, enticing, and powerful soul, a delicious one.

The Nine Tails suddenly makes a face, sensing where his demon servant mind goes, damn Sebastian’s insatiable thirst of rare souls and damn that blond mangy hokage for taking away his sinister other half, now any demon worth their salt will be yearning to taste his soul and they might not be too afraid to make the attempt. It’s fortunate that Sebastian is here now; he can deter any who tried, because his demon servant is selfish that way and Kurama is in no condition to thwart them himself with his limited physical vessel.

Wordlessly, he slashes open his right wrist with his sharp claws and offer the bloodied appendage to his demon servant, a reward for answering his summon and a renewal of their contract, to keep Sebastian chained to him—tighter than any physical chain could manage, let the demon tastes his life force, tastes his power in liquid form, and be in ecstasy.

Kurama lips quirks up at the reverent expression on his servant face, at the pleasure so vividly displayed when his lips touch the red liquid; how Sebastian’s normal amber colored eyes turns scarlet gold for a second before being covered by his eyelids as he closes his eyes to savor the taste.

“That’s enough Sebastian,” Kurama stops him when Sebastian sucks a bit too hard. Reluctantly, the demon servant releases his master hand, he straightens up and licks the last drop of blood from the corner of his lips, and then he kneels down.

The small wound heals instantly, Kurama looks down on his loyal powerful servant, certain that his orders will be followed to a T now, he gives the commands, “I want you to investigate the Uzumaki and the Namikaze family history and find anything that can be used as your fictional background, there is no other way for it. My vessel’s life is tied too closely with mine now and any damage to him will damage me too in some way, damn that golden mutt, if you appear from this child’s parent’s faction, very few people will be able question you, what with the extinction of the Uzumaki clan. His father came from a great family, an incredibly successful merchant family turned noble—their status raised by the Fire Lord himself, but they’re practically unheard of for three decades now—find out what happen to them.

“Prepare safe houses. When I told you this child have a lot of enemies, I didn’t exaggerate any of it. The entirety of Iwa hates his father, Kumo used to want his mother as a demon vessel, and the only ones in Konoha that don’t hate him are the ones that know the identity of his parents, which are very few.

“Then, you are to investigate the current political climate in this village as well as villages that holds my siblings. We used to be close as siblings, if you can believe me, but that didn’t last. Doesn’t mean I want to ignore their existence now, they can be a threat to me and my vessel. Konoha is at its lowest now—before, my each of vessel was well protected by their significant other, their ridiculously powerful mate; but now, my vessel is a vulnerable child not even two years old shunned by majority of the village, and his only protection is the squad of ninja indifferent to his fate, save few, too few of them.

“Next, I want you to look into the Ruins of Uzushiogakure, and find any salvageable scrolls, tomes, and books about the Sealing Art. I plan to gain a measure of independence and I can’t do that trapped inside. And compile profiles of each of people from this village with power and standing that have possible motive or design for my vessel. You have one week.”

“Yes, My Lord,” Sebastian accepts easily, as if traveling hundreds of miles to gather information, tracking every mention of sealing arts in the middle of ruined island so far of the west, then spying on each and every individual with power and tight security measures are some easy everyday tasks equivalent to dusting some rooms. Kurama is not surprised though, he’s perfectly aware of his demon servant’s unimpeachable skills. And now, those skills will reach new heights.

Before Sebastian has the chance to disappear to do his Lord’s bidding, his master tosses him a scroll, a memory, of a certain technique that will help him immensely in his endeavors; the jutsu known as the Shadow Clone technique.

Three days later, after much abuse to his shadow clones, Sebastian enters the gate Konoha with a new identity, mountains worth of information, stacks of chests filled with scrolls and tomes of the lost Sealing Arts, various keys to various holdfasts and safe houses, a new mansion for his masters, and some allies.

One Hell of a Butler indeed, Kurama smirks, satisfied.

 


	2. Sir Capable

The identity Sebastian takes is that of a servant of a demon descendant that are tied to the Uzumaki. Such tales does exist, about an Uzumaki Elder that tamed a storm and the demon that came with it. It was a heroic, epic, and heartwarming tales that end in tragedies with the death of everyone in the catastrophic invasion. But of course, Sebastian embellish the tale a little, how his fictional mother managed buy him enough time to escape with his life, and how for all this years he serve master to master and never found one worthy of his service.

A clever half lie that many doubt, but the one thing that finally lets him escape the interrogation room and be tentatively accepted as who he says he is—is the lost scroll of a great barrier seal that used to protect the island of Uzu, the seal was amusedly named “Uzu-kun”. It is believed that the barrier didn’t even waver under the onslaught of powerful attacks by the alliance of the three great shinobi villages, and the only thing that let them defeat the barrier was when they finally woke their sleeping agent and turned the spy onto the people that raised him, disabling the barrier from within.

This powerful barrier seals are now being studied to be applied to the Konoha proper, Jiraiya the Sannin is urgently called back to make sense of the overly complicated barrier seals, and Orochimaru is dragged from his research facilities for the same reason. The Toad Sage and Snake Clan contract holder later confirm the ingenuity of the seals; according to them the barrier will be able to withstand any physical assaults and will only crack when three tailed beasts worth of chakra attack it on a various specific points simultaneously. The barrier will also be able to recognize and neutralize subtle infiltration, because it recognize chakra signatures, their origin, their current mood, it can even read intentions. In a way, the “Uzu-kun” is alive, a silent, all knowing and powerful guardian of any large area it applied to. And to Konoha’s luck, the seal is going to be applied with a grand ceremony soon.

Sebastian has to track down a missing nin hiding in the Land of Moon for it. The most troublesome six hours of his long life. Simultaneously, he sent almost two thousands clone in various disguises to complete his missions. Several hundred clones combing the ruins of Uzushiogakure, then tracking the missing scrolls and tomes stolen by scavengers, missing nins, and other treasure hunters, he even took back some powerful artifacts from unworthy hands.

Few hundred of more clones for spying various people of power and standing including the Fire Lord and his courts then everyone with the title kage; add to that few hundred more shadow clones to compiles a detailed scroll of the political climate and profiling the players. Another few squads of Sebastian in disguise are tasked with securing safe houses and creating some very well hidden ones across the realm, it took a lot time from the allotted time-frame and money, but thankfully he’s adept at creating currency (and procuring treasures from worthless mortals).

The original Sebastian (after he comes back from the Land of Moon) and another hundred of his disguised clones leave for another important mission, to analyze Konoha and its inhabitants and to dig anything worth about the Fourth Hokage, Namikaze Minato. Where did he come from? Who are his family?—If they’re still alive at all, then what about his allies or friends?

* * *

 

They find the Namikaze family former residence in a village near the capital of fire country; it is a great abandoned manor with green rolling hills and a small forest surrounding it. Some questions to the locals bring forth the tale of the late Namikaze family.

The family back then consisted of the oldest—the heir of the Namikaze estate and business, Namikaze Tetsuya; his wife, and then their seven children, with the youngest later become the Fourth Hokage. Then there is his sister, Namikaze Setsuka, a spouse to one of the powerful lords advising the Lord of the Fire Country. The last, the youngest is Namikaze Tatsuya who deal with sketchy people and the locals don’t know what becomes of him, they’re not even sure whether Tatsuya is alive or not.

All of the inhabitants of that manor died, murdered, just a week after the youngest son, a six years old Minato, left the manor to Konoha. Some believe it was Tatsuya’s treachery, others believe it was a plot from the emperor advisors that didn’t like upstart family and trying to undermine the influence of the female Namikaze mingling among them.

None of them are sure about the theories though, one person even used to believe it was Minato’s doing until the small boy sent some of his servants to investigate the murder of his family—it could be a ruse, sure, but then Minato went and became the Fourth Hokage and died saving the village, and thus the theory about his dark nature gone with his death, because a person that love his village so much he died for it, he deems incapable of butchering his family in cold blood; besides, Minato was six at the time, only idiots would believe such rumor. ‘ _Which is you_ ,’ the clone thinks scathingly.

Sebastian’s clone can only shakes his head at the idiotic old geezer, oh how he can just to snap his fragile mortal neck to give mercy to the rest of the world from his idiocy. Then he does just that, and left the cooling corpse at the bottom of the stair, people will conclude the old man just had an unfortunate incident. The clone alters his disguise slightly and moves on to the next local for another questioning.

Sebastian tasks a pair of clones to track down Namikaze Tatsuya if he’s alive, or search out his grave if he’s dead. Another pair he orders to spy of the last of the sibling Namikaze in the imperial city only—to find out that she’s dead in a mysterious circumstance.

The clones dispel themselves to inform their original, it seems like the list of the things he has to do only increase with every passing hour. Nevertheless, it doesn’t matter; the investigation has to wait until he gets used to information overload and until he can create even more clones without feeling like he’s about to die a premature death.

* * *

 

Sebastian used the three days to prepare his identity and finish some of his many quests. He comes back to the village on the fourth day and this is now the second day since he comes back to the village, five days since his master bid him on the missions, and now he’s ready to get the vessel out of that orphanage.

Words spread fast across the village about a strange handsome man in strange handsome carriage with trains and trains of wagons following him into the village proper; and then about how his advances into the village is stopped by an ANBU squad—only to emerge from the T&I district the next day with not a hair out of place. Words even include the tidbit where the Hokage not so discreetly shook this man hands as if he’s an important ally or an ambassador from an important village.

They are puzzled when the man finally makes another appearance in an orphanage in the Hokage district, the man spends one whole hour in that building, then he emerge with the fox brat. They become even more puzzled at that. One of the outspoken villagers asks what he’s doing with the demon child rather patronizingly, as if a man of his standing doesn’t know that he’s doing, and that maybe he gets the wrong child to be adopted.

The handsome stranger just smiles at the man, then informs the crowd at large that his name is Sebastian and that he’s a loyal servant to the Uzumaki clan and in the capacity as the guardian of the clan, he’s picking up the heir of the Uzumaki, also known as the Nine Tails’ vessel. He also charmingly tells them to make way for the many, many wagons he has following him.

They all stop and gawk at him and his charge. He deliberately doesn’t use teleportation to let the village see them with all the pomp and fanfares. Let them see the child, this bright and curious child that he is, wriggling in his arm as if he likes nothing more than to jump off the carriage and testing his ability to walk or crawl around, as this is his first time outside, seeing the world around him, and it makes him very interested in everything, he crawls around the carriage, pulling at Sebastian hair, and any glittering object he can find on the patient butler, his chain from the pocket watch, his butler pin, his tie, and his shiny silver buttons.

When Naruto’s hands rest on either side of Sebastian’s face, Sebastian is struck with Naruto’s adorability once more; he grasps the child’s tiny hands, gaining his attention. Inquisitive blue eyes find a pair of reddish amber ones, and they stare at each other, ignoring the rest of the world. Here, a demon of a great notoriety is as calm as still water in front of a baby of a great infamy himself, there is a joke at the end of this but for all his clever remarks, Sebastian can’t find one appropriate for this situation.

The spell breaks when the baby utters his name quietly, as if believing that Sebastian is just like is many other imaginary friends that will leave him alone when he finally wakes up.

“Sebby,” the little one whispers his name like it is a great secret, and Sebastian’s shriveled black heart can only takes so much, thus he hugs the startled child and cuddles him for all his worth, eliciting a squeak and a giggle from the small child.

He only stops when his master enters his mind and commands him to stop that he’s doing at once with a horrified voice. “For the respect you held for me Sebastian, I command you to stop! Gods, didn’t you know that now I can feel what my vessel feels too?! I know I can’t prevent you from doing that again so I only ask you to give me a warning beforehand. So I can close my ‘windows’ first, so to speak.”

“Yes, My Lord, I shall remember that you abhor a display of affection,” Sebastian answers mock-solemnly.

“See that you do,” the great demon fox growls angrily as he retreats from his servant’s mind.

Sebastian then gently picks up Naruto from his lap and stands the small child just by the window so that he can see the sights pass by. His blue eyes dancing from curiosity to curiosity, everything is so new to him that he hardly able to makes sense on what he’s seeing. But it does not matter, the only thing that matter to his limited understanding is that he’s not alone and that feels good, and he has feeling that this ‘Sebby’ will not disappear anytime soon.

They arrive in front of massive iron gates, which open from within, by a clone of Sebastian in a disguise of the gate keeper. Not that anyone will figure that out, in facts, everyone in the entourage—except the baby of course—are Sebastian in disguise, just enough clones he can spare from his other ongoing missions. Some of the clones arrived ahead to prepare the manor house to receive their little lord.

The overgrown grass is trimmed into an acceptable height, the dense hedge bushes are trimmed into cute animal shapes, the courtyard swept and decorated with tasteful lampions and statues; the abandoned glass house is restored to its former glory, filled with healthy consumable plants and some rare exotic plants as well; the windows are opened, the rooms aired out then they’re are dusted; the floor are swept and mopped then polished and carpeted; the furniture are polished into perfection that even the wooden ones can be used as reflective objects. Last but not least, furniture with clothing or hides is replaced with new ones. All of that are done within an hour, just enough time for them to prepare the house to receive its new master.

It is an exhausting works on any normal mortal, so it is a good thing that Sebastian is neither normal nor mortal and that he has an army of clones to do his biddings. Sebastian looks at the newly cleaned manor and satisfied at what he’s seeing, he looks down at the petite lord in his arm then gesture with his other hand and says, “Welcome to the Whitecap Manor, this is now your house, Young Master.”

Naruto looks wide eye at the very big house in front of him. They passed some big manors on the way here, but Naruto didn’t pay attention then. The manor is a great white building with four floors with lots and lots of transparent glass windows, there are invisible seals on them that render them almost unbreakable—a new addition courtesy of Sebastian that has been learning on the art of sealing, the human style; it has a look of elegance but it has the design for practicalities. The manor also has a lot of hidden rooms, a dungeon, and a small lake at the back. All in all it is a magnificent residence fit for someone of Naruto’s status.

_But…_ Sebastian sighs inwardly; this place will be a lonely place to grow up, with too much space and too little inhabitants…

The demon stops in his track, making the baby look at him with a questioning eyes, _‘why did we stop? Didn’t you say this is my house now? I want to be inside right now!’_  His expression seems to say, Sebastian snorts, what an expressive face, he’ll be a terrible ninja or a really ingenious one when he grows up.

Sebastian wonders since when does he becomes so invested in the well being of his new master…even if the child is the vessel of his master, this is hardly a normal behavior of him.

What a perplexing child, to make a demon feels this way, he won’t be surprise if Naruto turns out to be the fated hero of some ancient prophecy.

Human touched by fate tends to be attracting allies left and right without even meaning to. He chuckles to himself, remembering those few chosen ones fondly; they all have powerful personalities and delicious souls to match. Maybe the mini lord will grow to have delightful soul one day and maybe he’ll even let him taste. For now though, the soul inhabiting the small body is still pure, untouched by the tragedies surrounding his existence, and he, Sebastian will see it grows.

Sebastian forgets that time in his musing, that the people in this realm have no new and pure souls as he believed, because the concept of reincarnation is very foreign to him, he doesn’t realize that the one soul in Naruto’s body has thousand years worth of memories and it only needed to be ‘unlocked’ for the memories to unleash themselves into Naruto’s psyche. And the day Sebastian witness this unlocking is the day he will believe in reincarnation and second chances.


End file.
